Bis(4-nitroanilines) in interactions through a π-conjugated bridge: conformational effects and potential molecular switchesElectronic supplementary information (ESI) available. CCDC 1003266 (PNA). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7nj02622f
Two molecules, 2,2′-(1,4-phenylenebis(ethyne-2,1-diyl))bis(4-nitroaniline) ( PNA ) and 2,2′-(1,4-phenylene-bis(ethyne-2,1-diyl))bis( N , N -diethyl-4-nitroaniline) ( PDNA ), built up from two p -nitroaniline " push-pull " nonlinear optical (NLO) chromophores slightly conjugated through a 1...
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Sprache: | eng |
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Zusammenfassung: | Two molecules, 2,2′-(1,4-phenylenebis(ethyne-2,1-diyl))bis(4-nitroaniline) (
PNA
) and 2,2′-(1,4-phenylene-bis(ethyne-2,1-diyl))bis(
N
,
N
-diethyl-4-nitroaniline) (
PDNA
), built up from two
p
-nitroaniline "
push-pull
" nonlinear optical (NLO) chromophores slightly conjugated through a 1,4-phenylenebis(ethyne-2,1-diyl) bridge have been synthesized and fully characterized. The crystal structure of
PNA
reveals that the ground (off) state conformation corresponds to the centrosymmetric anti-conformer in which the molecular hyperpolarizability (
β
) is equal to zero. A computational investigation reveals that, once submitted to an intense electric field (
E
), the two
p
-nitroaniline subunits are gradually aligned in the direction of the field with the appearance of a metastable (on) state (
β
≠ 0, when
E
= 0), stabilized by conjugation. A loop of hysteresis is observed during the on off cycles leading to a form of molecular bistability. The NLO response of
PNA
has been investigated at different field intensities by the electric-field induced second-harmonic (EFISH) technique to provide experimental evidence for this behavior.
DFT computation suggests that two dipolar chromophores in rotation around an organic bridge could be aligned by an electric field. |
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ISSN: | 1144-0546 1369-9261 |
DOI: | 10.1039/c7nj02622f |